The present invention relates in general to electrical power tools, and more particularly to a multipurpose alternating, direct current combination tool with a main body portion connectable to different types of interchangeable tool head portions.
The electric tool is a common tool with very widespread applications in households and factories. In the past, it has often been necessary to purchase multiple tools in order to perform multiple processes or tasks such as drilling, planing, shearing, grinding, and like, resulting in high purchase cost and carrying inconvenience. In order to overcome the drawbacks of high purchase expense and carrying inconvenience, many patents and documents have covered various forms of combination electric tools.
Chinese Patent No. ZL93220617.4, for example, discloses a type of electric tool assembly, wherein a main machine part of an electric motor is coupled with multiple different tool heads to drive different kinds of tools, so as to provide multipurpose functioning with one machine. However, that patent does not disclose how the tool head is coupled with the main machine part.
Chinese Patent No. ZL96217802.0 discloses a universal electric tool wherein two spring-biased round head pins are provided on the output shaft of an electric motor to couple the tool with the tool head. Although this arrangement is very convenient for replacing tool heads, the power transmission between the motor and tool head is through two contact points on the two round head pins. Hence, the power transmission efficiency will be affected to a certain degree and, due to repeated mounting and dismounting, the round head pins may become worn, and may result in injury to users.
Chinese Patent No. ZL97201237.0 discloses a combination type multipurpose electric tool, and sets forth a method of coupling the main machine part with a tool head. It can be noted from the technique disclosed by that patent, that the main machine part and tool head utilize male and female screw threads to make the coupling. This kind of coupling method is very inconvenient when replacing tool heads, and may easily damage the output shaft or electric motor.
It can be noted from the above-mentioned prior art that the coupling and power transmission of the main body with the tool head of multipurpose combination electric tools have disadvantages associated with their method of coupling and power transmission, and may cause injury to users. Hence, there continues to be a need for a multipurpose combination electric tool that is safe, reliable, and performs for users at an acceptable level of expectation.
It is an object of the present invention to provide a multipurpose combination electric tool with a locking mechanism for coupling a main body portion with a tool head portion to overcome the above-mentioned drawbacks of the prior art. The combination electric tool may be adapted to receive alternating and/or direct current.
The present invention divides the existing electric power tool into a main body portion and a tool head portion. The main body portion includes an electric motor, a speed control switch, a battery or other power source, and the like components. The tool head portion includes a speed control device, a direction change device, a transmission mechanism and the like components. The above-mentioned components are known in the prior art and therefore will not be further described.
According to the invention, the main body portion couples with the tool head portion through a locking mechanism and a power transmission device for transferring power from the main body portion to the tool head portion.
The locking mechanism comprises a thrust ring provided on the main body portion that is rotatable over a preset distance and a locking head provided on the tool head portion. A locking ring and a locking pad are also provided on the main body portion and are operably associated with the thrust ring.
The thrust ring is an annular ring with an outside rim and thrust ring levers extending from the outside rim and out of the housing of the main body portion. At least one fixing element is located on the thrust ring for fixing the locking ring against relative rotation. The outside diameter of the thrust ring should be sized to be received within the housing of the main body portion, so as to enable the thrust ring to rotate inside the housing.
The locking ring is an annular ring with an inner rim and inclined wedges provided on the inner rim. When the thrust ring is rotated, the locking ring can also rotate therewith due to the at least one fixing element.
The locking pad is an annular ring that is located adjacent one side of the locking ring. Bosses are provided on the annular ring and are inserted into slots in the housing of the main body portion to fix the locking pad to the housing.
A washer can be provided between the locking ring and locking pad for adjusting clearance.
The thrust ring, locking ring, locking pad and washer are all provided on a forward end portion of the main body portion and sleeved at the outer side of the electric motor output shaft.
The locking head is located at the rear end portion of the tool head portion and includes coupling lugs and a wedging slot located forward of the coupling lugs. The wedging slot receives the inclined wedges of the locking ring during rotation of the locking ring in one direction to tightly couple the main body portion with the tool head portion. Likewise, the inclined wedges of the locking ring can be removed from the wedging slot during rotation of the locking ring in the opposite direction to separate the main body portion from the tool head portion.
The power transmission device comprises an external spline fixed on the output shaft of the electric motor and an internal spline located inside the tool head portion. The internal and external splines are provided with guiding faces to mate with each other. In use, the internal spline is inserted through cooperation of the guiding faces into the external spline to transmit power from the output shaft to the tool head portion.
The present invention can form different tools with a single main body portion and different interchangeable tool head portions by merely changing one tool head portion for another. The tool head portions can be in the form of an electric drill head assembly to be rapidly used as an electric drill; the tool head portion can be in the form of a triangular sanding head assembly to be used as a sanding machine; the tool head portion can be in the form of an angular grinding machine head assembly to be used as angular grinding machine; the tool head portion can be in the form of a cement or concrete is mixing assembly to be used as a cement or concrete mixing machine; the tool head portion can be in the form of a reciprocating-type sawing machine to be used as reciprocating sawing machine, and so on. The various tool head portions mentioned above are well known and, in accordance with the present invention, can be easily connected to and disconnected from the main body portion.